<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="tranfer.js"></script>
    <style>
        .slidebar {
            position: relative;
        }
        
        span {
            position: absolute;
            background-color: aqua;
            padding: 0;
            margin: 0;
        }
        
        .con {
            position: absolute;
            background-color: purple;
            z-index: -1;
            left: -44px;
        }
    </style>
</head>

<body>

    <div class="slidebar">
        <span>-&gt;</span>
        <div class="con">问题描述</div>

    </div>
    <script>
        var slidebar = document.querySelector('.slidebar');
        var con = document.querySelector('.con');
        slidebar.addEventListener('mouseenter', function() {
            tranfer(con, -10);
        })
    </script>
</body>

</html>